The medium size Boat Sponge helps to remove that unwanted pool of water that manages to collect in your kayak. Paddling in whitewater or the sea, this sponge will lift out sand and moisture from the bottom of your boat that traditional bilge pumps leave behind. It can be used with a bilge pump or on its own to keep your boat dry and clean. 8.75in L x 4.5in W x 2.75in thick